module: centralize builtin exposure policies

[sjungwon03]

Builtin exposure rules are currently split between realm.js and
separate setup functions in pre_execution.js for each option-gated
builtin.

Move the JavaScript loader's scheme and option-gating policies into one
table, and let pre-execution apply them after option initialization.

This intentionally keeps the policy in the JavaScript loader instead of
deriving it from native option registration. Native options do not
describe which builtins they expose: one option may enable multiple
builtins, while other options are unrelated to builtin exposure.
Code-cache categorization also has a separate responsibility. Adding
exposure metadata there would duplicate loader policy across the native
and JavaScript boundaries.

The policy test validates every declared builtin ID and option, as well
as defaults, --no-experimental-*, NODE_OPTIONS, and command-line
precedence. It also covers CommonJS, ESM, Workers, child processes, and
process.getBuiltinModule().

A builtin omitted entirely from the policy table cannot be detected
automatically because there is no independent native mapping between
options and builtins. Centralizing the loader-owned policy reduces that
risk without introducing a second source of truth in C++.

Refs: #65418
Refs: #65964
Refs: #65920
Refs: #65840

Tests:

• make -C out -j4 node
• python3 tools/test.py -j4 parallel/test-module-builtin-policies parallel/test-module-builtin-experimental parallel/test-sqlite

[nodejs-github-bot]

Review requested:

• @nodejs/loaders
• @nodejs/startup

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.37%. Comparing base (96ee81c) to head (b2e6b82).
⚠️ Report is 22 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #66292      +/-   ##
==========================================
+ Coverage   90.35%   90.37%   +0.01%     
==========================================
  Files         790      790              
  Lines      273814   274230     +416     
  Branches    52382    52490     +108     
==========================================
+ Hits       247409   247823     +414     
+ Misses      16906    16888      -18     
- Partials     9499     9519      +20     

Files with missing lines	Coverage Δ
lib/internal/bootstrap/realm.js	97.09% <100.00%> (+0.10%)	⬆️
lib/internal/process/pre_execution.js	96.76% <100.00%> (+0.09%)	⬆️
lib/internal/test/binding.js	89.74% <100.00%> (+1.86%)	⬆️

... and 54 files with indirect coverage changes

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[daeyeon]

This list could become stale as policies change. For example, if these modules no longer need experimental flags while other modules still do, the test could pass without the coverage described above.